Technical Abstract:
For more than twenty years, various industrial, governmental, and academic laboratories have developed and refined genetic engineering strategies aimed at manipulating lipid metabolism in plants and microbes. The goal of these projects is to produce renewable specialized oils that can effectively compete with or completely replace traditional nonrenewable feedstocks. The target oils produced in most of these projects are used in either nutritional or industrial applications. Some nutritional breeding programs seek to improve the physical properties and shelf-life of oils used in cooking and frying applications. These objectives are generally accomplished by reductions in the levels of saturated and polyunsaturated fatty acids, accompanied by relative increases in monounsaturated fatty acids. Recently, much focus has been directed towards creating “fish oils” in plants. Fish oils positively affect eye and heart health, and many aspects of neurological development in infants, due to the high levels of polyunsaturated very long-chain (C20-C22) fatty acids. Some consumers have become reluctant to consume many types of fish, or the oils derived from them, due to the overfishing of certain species and evidence of increased levels of heavy metals and other toxins found in some types of fish and other seafood. Therefore, alternative sources of these oils must be found or created, and engineering of plants or microbes to produce fish-like oils offers an attractive, low-impact, renewable source of these valuable commodities. Much progress has been made in this exciting field in recent years, and excellent reviews summarizing these results have recently been published; therefore, these topics will not be discussed in detail here. This chapter will focus on the efforts to engineer plants and microbes to produce industrially useful oils.